Pregnant women exposed to flouride are more likely to have kids with low IQ, study shows

The major study is the first of its kind; it involved researchers from Canada, US and Mexico

The researchers analyzed data on 300 mother-child pairs from Mexico

They found every 0.5 milligram-per-liter increase of flouride in a pregnant woman’s urine marked a drop in intelligence scores for their children later in life

Experts warn the study, published today, shows flouride is particularly dangerous for brain development during gestation

Pre-natal exposure to fluoride is linked to lower measures of intelligence in children, an unprecedented study has found.

Researchers tracked data on nearly 300 mothers and their children in Mexico, testing the kids’ cognitive development twice in 12 years.

They found children were not affected by drinking flouride themselves, but tended to have low IQ scores on tests if their mothers flouride in their urine before childbirth.

Every 0.5 milligram-per-liter increase of flouride in a pregnant woman’s urine marked a drop in intelligence scores for their children later in life.

Experts warn the study, published today, shows flouride is particularly dangerous for brain development during gestation.

The research, the first of its kind, involved researchers from the world’s leading medical centers, including Harvard, McGill University, the University of Michigan, and the National Institute of Public Health of Mexico.

‘Our study shows that the growing fetal nervous system may be adversely affected by higher levels of fluoride exposure,’ said Dr. Howard Hu, the study’s principal investigator and professor of environmental health, epidemiology and global health at the Dalla Lana School of Public Health.

‘It also suggests that the prenatal nervous system may be more sensitive to fluoride compared to that of school-aged children.’

Flouride first took off as a bone-protected chemical 60 years ago.

Over the years, it has been added to tap water and dental products – as well as table salt and milk – in the US and Canada, tipped as a health boost.

However, a growing swell of research has emerged in the last few years showing water flouridation may have some cripplingly dangerous side effects, particularly for children’s brains.

While flouride is not added to the tap water in Mexico, many are exposed to the chemical naturally as it infuses water in the pipes, and is added to some salts.

The study analyzed data from 287 mother-child pairs in Mexico City that were part of the Early Life Exposures in Mexico to Environmental Toxicants (ELEMENT) project, which recruited pregnant women from 1994 to 2005 and has continued to follow the women and their children ever since.

The research team analyzed urine samples that had been taken from mothers during pregnancy and from their children between six and 12 years of age to reconstruct personal measures of fluoride exposure for both mother and child.

‘This is significant because previous studies estimated exposures based on neighbourhood measurements of drinking water fluoride levels, which are indirect and much less precise measures of exposure,’ said Dr Hu.

‘They also looked at children’s exposures instead of prenatal exposures or had much smaller sample sizes of subjects to study.’

The researchers then analyzed how levels of fluoride in urine related to the children’s verbal, perceptual-performance, quantitative, memory, and motor abilities at age four and once more between the ages of six and 12.

Analyses were adjusted for other factors known to impact neurodevelopment, such as gestational age at birth, birthweight, birth order, sex, maternal marital status, smoking history, age at delivery, IQ, education, socioeconomic status and lead exposure.

There are some known side effects of fluoride.

For example, dental defects like mild staining are common among those ingesting recommended levels of fluoride in the United States and Canada.

Skeletal fluorosis – excessive accumulation of fluoride in the bones – is much less common and only observed at levels of fluoride in the water that are more than five to 10 times higher than those recommended.

‘Relatively little is known, with confidence, about fluoride’s impact on neurodevelopment,’ said Hu.

With regard to the study’s implications for populations in North America, researchers found that urinary fluoride levels in pregnant women were somewhat higher than, but within the general range of, urinary fluoride levels seen in non-pregnant general populations in Canada and the United States.

However, in Dr. Hu’s opinion, the findings do not provide enough information to suggest there is no safe level of fluoride exposure.

‘The potential risks associated with fluoride should be further studied, particularly among vulnerable populations such as pregnant women and children, and more research on fluoride’s impact on the developing brain is clearly needed.’